That command seems fine to me, I just miss the --standalone argument but I tested it using exactly the command you used and it is fine, letsencrypt is smart enough to see that you want to use standalone method.

Checking your log I can see a KeyboardInterrupt and that is because you cancelled the process… maybe you hit Ctrl-C in the middle of the process.

Try it again but first, update your letsencrypt-auto client. If you downloaded it using git clone go to the dir where it is installed and perform a git pull and the just a letsencrypt-auto --version to update the virtualenv (the virtualenv is /root/.local/share/letsencrypt/)

For example, if you installed it on /root/letsencrypt/:

cd /root/letsencrypt/
git pull
./letsencrypt-auto --version

Once finished you can try again the same command you posted (remember to stop your webserver before launch the standalone method).